There is a clinical need for new neurovascular imaging techniques for the diagnosis, staging, and monitoring of acute stroke and sub-acute stenoses, arterial-venous malformations (AVMs), and aneurysms, among others. Together, these etiologies frequently manifest in acute stroke and kill over 130,000 people per year with an estimated cost the US healthcare system of over 36.5 billion dollars per year. A reliable and non-invasive neurovascular stress test, similar in concept to a cardiac stress test, would revolutionize cerebrovascular imaging and stroke prevention. It is well known that perfusion imaging, combined with a means of altering cerebral perfusion pressure or cerebrovascular resistance, can measure a patient's cerebrovascular reserve and predict the risk of stroke. Current neurovascular imaging techniques suffer from limitations in radiation exposure, safety, speed, sensitivity, and specificity that prevent their use in measuring cerebrovascular reserve. Magnetic particle imaging (MPI) is a new imaging technology that answers a clinical need for a safe, rapid 3D perfusion and 3D angiography technique without ionizing radiation or toxic tracers to image intracranial diseases such as stenosis (stroke), aneurysm, vasospasms and malformations. The MPI tracer is made with Iron Oxide (SPIO), significantly safer than Iodine (used in CT and fluoroscopy), and Gadolinum (used in MRI). The safe tracer and absence of harmful radiation leads to reduced long term medical costs for patient undergoing diagnostic angiography, and especially patients undergoing repeated diagnostic angiography procedures associated with long term care. MPI produces absolutely no signal from overlying tissues creating a positive contrast and quantitative angiography images or real time perfusion with unprecedented contrast to- noise and signal-to-noise. Successful completion of a human brain imager will mark the beginning of a new field of diagnostic imaging comparable in scope to the introduction of MRI, CT, or Ultrasound. This project aims to develop the first high resolution real time MPI system tailored for clinical cerebrovascular imaging. The proposed system will be the world's highest sensitivity and highest resolution tomographic MPI scanner. In Phase I of this SBIR, we will complete the main magnet design, build a 1/4 scale prototype, and develop our manufacturing plan. In Phase II we will construct the magnet and obtain phantom and animal images. In Phase III we will perform animal and then human testing